Island submount and a method thereof
An island submount used for carrying at least one light-emitting element having at least one electrical contact. The island submount includes a substrate, at least one island structure having a top surface and an inclined surface, and a conductive layer. The island structure is located on the substrate and corresponds to the electrical contact. The conductive layer is formed on the surface of the island structure and at least covers the top surface, so as to be electrically connected with the electrical contact. The island submount is capable of enhancing the light extraction efficiency of the light-emitting element, and avoids the energy loss due to re-absorption when the light emerging from below the light-emitting element is reflected back to the light-emitting element.
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This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 0961364445 filed in Taiwan, R.O.C. on Sep. 28, 2007, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of Invention
The present invention relates to a submount, and more particularly to a submount having an island structure used for carrying a light-emitting element.
2. Related Art
The light-emitting principle of light-emitting diodes (LEDs) is to form a p-n junction with different doping modes. When electrons and holes are combined, the energy is released in the form of light, and the light is substantially a set of infinite multi-point light sources. LEDs are advantageous in high durability, long service life, light weight, and low power consumption. Besides, LEDs do not contain hazardous substances like mercury. Therefore, the illumination market has a high expectation on LEDs.
The light-emitting efficiency of LEDs is generally referred to as the external quantum efficiency (EQE) of an element, which is a product of the internal quantum efficiency (IQE) and light extraction efficiency (LEE) of the element. The IQE of an element is actually the electric-optical conversion efficiency of the element, which is mainly relevant to the characteristics of the element, such as the energy band, defects and impurities of the material of the element, as well as the expitaxy composition and structure of the element. The LEE of an element is the number of the photons generated inside the element that can be actually measured outside the element after being absorbed, refracted, and reflected by the element. Thus, factors related to the LEE includes the absorption coefficient and refractive index of the material of the element, the geometrical structure and surface roughness of the element, the refractive index difference between the element and the packaging material, and the type of the element packages, and so on. The product of the above two efficiencies is the light-emitting effect of the entire element, i.e., the EQE of the element.
Besides the prior art of face-up architecture, the face-down flip-chip type packages are the main trend of the future development, since the face-down flip-chip type packages can significantly improve the heat dissipation and light extraction effect. Currently, the flip-chip architecture may be classified into to two popular types including the thin film LED and the flip-chip LED. The thin film LED is mainly formed by turning over an expitaxy layer plated with a reflective layer to be fixed to a submount by a connection layer, and then stripping the growth substrate and roughening its upper surface. The flip-chip LED has a similar architecture as the above thin film LED. The main difference therebetween is that the flip-chip LED is fixed onto a submount through a plurality of metal balls, and thus a space for emerging light is formed between the expitaxy layer and the submount, so as to reduce the amount of absorption of the light emerging from below the flip-chip LED when being reflected back to the flip-chip LED.
To avoid the absorption of the light from below the light-emitting element to reflect back to the light-emitting element, the present invention provides an island submount which is a substrate having an island structure and a method thereof.
The island submount of the present invention is used for carrying at least one light-emitting element having at least one electrical contact. The island submount includes a substrate, at least one island structure having a top surface and an inclined surface, and a conductive layer. The at least one island structure is located on the substrate and corresponding to at least one electrical contact of the light-emitting element. The top surface of the island structure is corresponding to the electrical contact of the light-emitting element, and the inclined surface of the island structure is used to reflect and guide the light emerging from below the light-emitting element to be emitted from the side. The conductive layer is formed on the surface of the island structure and at least covers the top surface, and is electrically connected to the electrical contact of the light-emitting element.
A method for fabricating an island submount, wherein the island submount is used to carry at least one light-emitting element having at least one electrical contact, the fabrication method comprising providing a substrate, forming at least one island structure having a top surface and an inclined surface, wherein the island structure is corresponding to the electrical contact, forming a conductive layer on the substrate, wherein the conductive layer at least covers the top surface, and connecting the conductive layer covered with the top surface to the electrical contact.
The island submount and the method thereof of the present invention is used to guide the light from below the light-emitting element to be emitted from the side, so as to avoid re-absorption when the light is reflected back to the light-emitting element, thus enhancing the overall LEE of the light-emitting element.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the present invention, and wherein:
The features and practice of the present invention will be illustrated in detail below with the accompanying drawings.
Referring to
The substrate 23 is made of a thermal conductive material, such as semiconductor, ceramic, or metal material.
The island structure 24 is formed on the substrate 23 and corresponding to the electrical contact 22 of the light-emitting element 21. The island structure 24 has a top surface 26 and an inclined surface 27.
The conductive layer 25 is covered on the top surface 26 of the island structure 24, for electrically connecting to the electrical contact 22 of the light-emitting element 21 corresponding to the island structure 24. The conductive layer 25 is electrically connected to the electrical contact 22 of the light-emitting element 21 through a connection layer 28. The connection layer 28 is made of an electrical conductive material. The conductive layer 25 is made of an electrical conductive material.
The island submount 100 of this embodiment further includes a reflective layer 29. The reflective layer 29 not only covers the inclined surface 27 of the island structure 24, but also covers the surface of the substrate 23, so as to appropriately reflect more lights. The reflective layer 29 is used to reflect and guide the light emerging from below the light-emitting element 21 carried by the island submount 100 to be emitted from the side. The reflective layer 29 is made of a reflective material.
The inclined surface 27 is a flat surface or a curved surface. Referring to
Referring to
The substrate 123 is made of a thermal conductive material, such as semiconductor, ceramic, metal material, glass fiber, or bakelite.
The two island structures 124a, 124b are formed on the substrate 123. Each of the island structures is corresponding to an electrical contact of the light-emitting element. That is, the two island structures 124a, 124b are respectively corresponding to the two electrical contacts 122a, 122b of opposite electrical properties of the light-emitting element 121. The two island structures 124a, 124b respective have top surfaces 126, 128 and inclined surfaces 127, 129.
The two conductive layers 125a, 125b are made of an electrically conductive and reflective material. The two conductive layers 125a, 125b are respectively covered on the top surfaces 126, 128 and the inclined surfaces 127, 129 of the two island structures 124a, 124b. The two conductive layers 125a, 125b respectively covered on the top surfaces 126, 128 are electrically connected to the two electrical contacts 122a, 122b of opposite electrical properties. The two conductive layers 125a, 125b are electrically connected to the two electrical contacts 122a, 122b of opposite electrical properties through connection layers 130a, 130b. The connection layers 130a, 130b are made of an electrical conductive material. The two conductive layers 125a, 125b are disconnected between the two island structures 124a, 124b.
The third embodiment of the present invention is disclosed above and is not intended to limit the number of the elements, such as the light-emitting element, the electrical contact, the conductive layer, and the island structure of the present invention. The number of the aforementioned elements may be one or more. Referring to
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The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Claims
1. A light emitting device comprising: a substrate; at least one two-island structure having two separate island structures and located on the substrate, each of the two separate island structures of the at least one two-island structure having a top surface and an inclined surface; a conductive layer, disposed on the substrate and at least covering the top surface and an inclined surface of each of the two separate island structures; and a light emitting element having at least two electrical contacts of opposite electrical properties which are each electrically connected with the conductive layer, and the light emitting element having a bottom surface facing the two-island structure, wherein the bottom surface of the light emitting element extends across the inclined surfaces and the top surfaces of the two separate island structures, each of the two separate island structures of the two-island structure corresponds to one of the two electrical contacts, respectively, and the conductive layers is disconnected between the two separate island structures of the two island structure.
2. The light emitting device as claimed in claim 1, wherein the inclined surface is a flat surface.
3. The light emitting device as claimed in claim 1, wherein the inclined surface is a curved surface.
4. The light emitting device as claimed in claim 1, further comprising a channel penetrating from the top surface of the island structure to the other side of the substrate, and wherein the channel has an electrical conductive substance connected to the conductive layer on an inner side thereof, so as to electrically connect the electrical contact to the other side of the substrate.
5. The light emitting device as claimed in claim 1, further comprising a reflective layer covering the inclined surface and a surface of the substrate having the island structure.
6. The light emitting device as claimed in claim 1, wherein the conductive layer further covers the inclined surface and a surface of the substrate having the island structure.
7. The light emitting device as claimed in claim 5, further comprising a transparent protection layer covering the reflective layer corresponding to the inclined surface and the surface of the substrate having the island structure, and wherein the transparent protection layer is capable of allowing the light emitted by the light-emitting element to pass through.
8. The light emitting device as claimed in claim 6, further comprising an insulating layer disposed between the conductive layer and the substrate.
9. The light emitting device as claimed in claim 6, further comprising a transparent protection layer covering the conductive layer corresponding to the inclined surface and the surface of the substrate having the island structure, and wherein the transparent protection layer is capable of allowing the light emitted by the light-emitting element to pass through.
10. The light emitting device as claimed in claim 8, further comprising a reflective layer covering the conductive layer corresponding to the inclined surface and the surface of the substrate having the island structure.
11. The light emitting device as claimed in claim 10, further comprising a transparent protection layer covering the reflective layer corresponding to the inclined surface and the surface of the substrate having the island structure, and wherein the transparent protection layer is provided for the light emitted by the light-emitting element to pass through.
12. The light emitting device as claimed in claim 11, wherein the transparent protection layer is at the same level of a light output plane below the light-emitting element, for carrying the light-emitting element.
13. A method for fabricating a light emitting device, comprising: providing a substrate; forming at least one two-island structure having two separate island structures, each of the island structures of the at least one two-island structure having a top surface and an inclined surface; forming conductive layers on the substrate, wherein the conductive layers at least covers the top surface and inclined surface of each of the two separate island structures; and covering a light emitting element having at least two electrical contacts of opposite electrical properties, the light emitting element covering over the inclined surfaces and the top surfaces of the two separate island structures, connecting the conductive layers to the electrical contacts of the light emitting element, where each of the two separate island structures of the two-island structure corresponds to one of the two electrical contacts of opposite electrical properties, and the conductive layers are disconnected between the two separate island structures of the two-island structure.
14. The method for fabricating the light emitting device as claimed in claim 13, further comprising forming a reflective layer after the step of forming at least one conductive layer, wherein the reflective layer covers both the inclined surface and a surface of the substrate having the island structure.
15. The method for fabricating the light emitting device as claimed in claim 14, further comprising forming a transparent protection layer after the step of forming a conductive layer, wherein the transparent protection layer covers the reflective layer corresponding to the inclined surface and the surface of the substrate having the island structure.
16. The method for fabricating the light emitting device as claimed in claim 13, wherein the conductive layer covers both the inclined surface and a surface of the substrate having the island structure.
17. The method for fabricating the light emitting device as claimed in claim 16, further comprising forming a transparent protection layer after the step of forming a conductive layer, wherein the transparent protection layer covers both the conductive layer corresponding to the inclined surface and the surface of the substrate having the island structure.
18. The method for fabricating the light emitting device as claimed in claim 16, further comprising forming an insulating layer before the step of forming a conductive layer, wherein the insulating layer is disposed between the island structure and the conductive layer.
19. The method for fabricating the light emitting device as claimed in claim 18, further comprising forming a reflective layer after the step of forming a conductive layer, wherein the reflective layer covers both the conductive layer corresponding to the inclined surface and the surface of the substrate having the island structure.
20. The method for fabricating the light emitting device as claimed in claim 19, further comprising forming a transparent protection layer after the step of forming a reflective layer, wherein the transparent protection layer covers both the reflective layer corresponding to the inclined surface and the surface of the substrate having the island structure.
21. The method for fabricating the light emitting device as claimed in claim 20, wherein the transparent protection layer is at the same level of the conductive layer on the top surface, for carrying the light-emitting element.
22. The method for fabricating the light emitting device as claimed in claim 13, after the step of forming at least one island structure, further comprises forming a channel penetrating from the top surface of the island structure to the opposite side of the substrate from the island structure, wherein the channel has an electrical conductive substance on an inner side thereof, and wherein the electrical conductive substance electronically connects the electrical contact to the other side of the substrate.
23. A light emitting device, comprising: a substrate; a two-island structure located on the substrate, each of the island structures of the two-island structure having a top surface and an inclined surface; two conductive layers, each conductive layer covering the top surface and inclined surface of each of the island structures, respectively; and
- a light emitting element including two electrical contacts of opposite electrical properties, where one of the two electrical contacts is located on the top surface of one island structure of the two-island structure and the other one of the two electrical contacts is located on the top surface of the other one island structure of the two-island structure, with the two electrical contacts are respectively in contact with the conductive layers on the top surfaces.
24. A method for fabricating a light emitting device, comprising:
- providing a substrate; forming a two-island structure on the substrate, each of the island structures of the two-island structure having a top surface and an inclined surface;
- forming two conductive layers on the top surface and inclined surface of each of the island structures, respectively; and disposing the light-emitting element on the top surfaces, the light emitting element including two electrical contacts, where each one of the two electrical contacts is located on a top surface of the two island structures, so as to connect the conductive layers disposed on the top surfaces.
25. A light-emitting element array, including:
- a substrate; multiple island structures located on the substrate, each of the island structures having a top surface and an inclined surface; multiple conductive layers, which cover each of the top surfaces and inclined surfaces of the multiple island structures, respectively; and
- multiple light-emitting elements each being located on the top surfaces of at least two of the multiple island structures, where each of the multiple light emitting elements including two electrical contacts, each of which is connected to one top surface of the at least two of the multiple island structures so as to connect the conductive layers of the at least two multiple island structures.
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- SIPO; Office Action in related foreign application (TW 096136445) to which priority is claimed by the present application; Jan. 8, 2010.
Type: Grant
Filed: Nov 30, 2007
Date of Patent: Jan 11, 2011
Patent Publication Number: 20090085050
Assignee: Industrial Technology Research Institute (Hsinchu)
Inventors: Yih-Der Guo (Hsinchu), Jenq-Dar Tsay (Hsinchu), Po-Chun Liu (Hsinchu)
Primary Examiner: Victor A Mandala
Assistant Examiner: Scott Stowe
Attorney: Workman Nydegger
Application Number: 11/948,464
International Classification: H01L 33/48 (20100101);